1. Field of the Invention
The invention is directed to a torsional vibration damper with a main damper and a predamper, especially for a clutch disk of a motor vehicle friction clutch.
2. Description of the Related Art
A prior art torsional vibration damper of a clutch disk having a main damper arrangement and a predamper arrangement which is arranged axially adjacent to the main damper arrangement is known from DE 44 30 261. The main damper arrangement of the prior art device is dimensioned for load operation and has two disk arrangements which are rotatable relative to one another about the axis of rotation of the clutch disk. A first of the two disk arrangements comprises two side disks with a flange ring arranged between them and separating the two side disks by an axial distance from one another. The side disks are fixedly connected with the flange ring by a plurality of rivets offset in the circumferential direction to form a unit. The flange ring is coupled via a toothing so as to be fixed with respect to rotation, but so as to have rotational play, with a hub that is mountable on an input shaft of a transmission of the motor vehicle. The second of the two disk arrangements includes a central disk arranged axially between the side disks so as to be rotatable relative to the side disks. The central disk includes clutch friction facings and is coupled via first spring elements with the side disks in a frictional-elastic manner.
The predamper arrangement of this prior art device comprises an input component and an output component which are coupled with one another in a torsionally elastic manner via second spring elements which are dimensioned for idling operation. The output component is connected with the hub so as to be fixed with respect to rotation relative to it. The input component has recesses which correspond to the arrangement of the rivet heads in the side disks of the main damper arrangement and to their dimensions and is connected in a rotatably fixed manner with the main damper by mounting on the rivet heads. For the purpose of calibrating the rivet heads, these rivet heads are formed by a one-piece tool which simultaneously comprehends all of these rivet heads, so that the dimensions of the rivet heads and their distance from one another are determined by the tool. Since the tolerances of the tool can be closely dimensioned, tolerances of the rivet heads can be achieved which comparatively closely follow the close tolerances of the cutouts of the predamper input component.
Although a torsional vibration damper of the type known from DE 44 30 261 is inexpensively assembled, the riveting produces a nondetachable connection. Therefore, once it has been assembled, this torsional vibration damper cannot be disassembled again. This can be disadvantageous if it is determined by an operational check after assembly that the spring tolerance or damping tolerance is not maintained and therefore the torsional vibration damper must be disassembled again. Disassembly is only possible by drilling open the rivets, so that this torsional vibration damper must then be discarded as waste.
Reference DE 43 09 477 discloses another prior art torsional vibration damper of a friction clutch which substantially differs from the torsional vibration damper of DE 44 30 261 in that the main damper arrangement is not held together by rivets. The side disks of the main damper arrangement are welded to the flange ring in this case and the main damper arrangement is fixed axially in one direction by the predamper arrangement which is connected with the hub so as to be fixed with respect to rotation relative to it and is fixed axially by caulking. In the other direction, the main damper arrangement is fixed axially by a retaining ring, so that this torsional vibration damper can also be disassembled again. A disadvantage of this prior art device is that the loading capacity with respect to axial forces is limited because this torsional vibration damper is fixed axially in the direction of the predamper arrangement by a weak caulk point. When loaded by strong axial forces, this caulk point would break, so that the predamper arrangement and the main damper arrangement which is axially fixed by the latter would detach from the hub and toothing arranged on the latter, resulting in the loss of operability of the entire clutch.